Spin-orbit coupling and beyond in Chiral-Induced Spin Selectivity

Abstract

Chiral-Induced Spin Selectivity (CISS) describes the emergence of spin-polarized electron transport in chiral systems without magnetic fields—a remarkable effect in light-element materials with weak in- trinsic spin–orbit coupling (SOC). This mini-review analyzes the microscopic origins of CISS, highlighting how molecular chirality, local electric fields, and dynamic distortions enhance effective SOC and drive spin-dependent transport. We critically assess existing models in terms of their symmetry constraints, phenomenologi- cal assumptions, and compliance with Onsager reciprocity. Recent developments combining relativistic quantum mechanics and com- plete multipole representations reveal a direct link between chirality density and spin current pseudoscalars, suggesting a field-theoretic foundation for CISS. These insights could help positioning light- element chiral nanomaterials as tunable platforms for probing and engineering spin-selective phenomena at the nanoscale.